Many types of fuel filters and separators are known in the prior art. A popular type of fuel filter construction is one that has a housing which encloses a replaceable filter element. Fuel used to power a self-propelled vehicle, such as gasoline or diesel fuel, is cleansed of impurities as it passes through filter media of the filter element. The filter media captures many of the impurities that are removed from the fuel. Other impurities collect on the surface of the media and fall downward into a bottom area of the filter housing from which they may be periodically removed through a drain valve.
Periodically the filter element must be replaced. Such periodic replacement ensures that the filter element will not become so loaded with impurities that fuel flow is restricted. Replacing the element also ensures that impurities are removed from fuel before it is delivered to other fuel system components such as fuel injection pumps and fuel injectors, where such contaminants may cause severe damage.
Changing filter elements may pose problems however. One common problem is that disturbance of the spent element during replacement may cause collected impurities to fall off the element. In some designs, these impurities may travel into the outlet of the filter housing. As a result these contaminants may reach the components downstream in the fuel system.
Another problem with certain prior art fuel filter constructions is that changing the element may require a mechanic to have skin contact with the fuel. It is desirable to minimize such contact when changing a filter element.
To reduce these problems, the filter assembly element shown in U.S. Pat. No. 4,836,923, owned by the Assignee of the present invention, was developed. This filter assembly includes a replaceable filter element that is attached to a removable cover. This construction enables changing the element while avoiding skin contact with fuel.
A further advantage of this prior art design is that it has an internal standpipe with an opening at the top. When the element is removed from the housing, the fuel level in the housing falls below the opening to the standpipe. As a result, the impurity-laden fuel left in the housing is less likely to reach the outlet. Likewise when a new element is installed in the housing, only fuel that has been purified by passing through the media of the element is enabled to reach the opening and pass out of the assembly.
While this prior design has many advantages, it has some shortcomings. First, if the filter element is not removed carefully, impurity-laden fuel in the housing or from the outer surface of the element may fall into the opening in the standpipe. If this happens, some impurities may reach the downstream components of the fuel system.
A further shortcoming of the prior art design is that the cover is discarded with each spent element. This is undesirable from a conservation and solid waste standpoint. It is generally desirable to minimize the amount of material discarded, particularly if a discarded element must be treated as hazardous waste. The cover also represents a portion of the cost of the replacement element. As a result this design adds cost to the replacement element.
Sometimes individuals who do not care about maintaining the vehicle on which the prior art filter assembly is used, may separate the element from the attached cover portion and install the cover on the housing without the element. This causes the vehicle to operate without fuel filtration until the problem is discovered. If the vehicle is operated for an extended period of time in this condition, damage to fuel system components may occur.
Thus there exists a need for fuel filter assembly with a replaceable element that has increased reliability, reduces waste, is lower in cost, and minimizes the risk of skin contact during element changes.